Use of Computed Tomography to Distinguish Thrombus from Pannus on a Bioprosthetic Aortic Valve.

Bioprosthetic valve thrombosis was previously considered to be a relatively rare complication of surgical or transcatheter bioprosthetic valve replacement. Although echocardiograms can reliably show the characteristic findings of prosthetic valve stenosis, differentiating between thrombus formation and pannus overgrowth as the underlying cause of prosthetic valve dysfunction can be challenging. We present the case of a 75-year-old man who underwent transthoracic Doppler echocardiography in the presence of an elevated valvular gradient 2 years after his aortic valve had been surgically replaced with a bioprosthesis. The echocardiographic findings suggested prosthetic valve stenosis. Cardiac computed tomography, performed to distinguish between thrombus formation and pannus overgrowth, revealed hypoattenuated leaflet thickening and reduced leaflet mobility, which suggested thrombus. After the patient took oral anticoagulants for 3 months, images showed complete resolution of the previous abnormalities, thus confirming the diagnosis of bioprosthetic valve thrombosis. We found cardiac computed tomography valuable when evaluating our patient who had an elevated prosthetic valve gradient.